Resonator and method of making it



Dec. 10, 1968 J. c. ARTHUR ETAL 3,415,336

RESONATOR AND METHOD OF MAKING IT Filed NOV. 14. 1966 2 Sheets-Sheet l I I W! i QM; I S H i a -13 i i s .0: s Fig. 2

i l i I s |Q 40 :ii S w! I Q: E 5 i S 3 42 I I E i JAMES cffifififi i BY RAYMOND L. PLACEK w dwhiw ATTORNEYS United States Patent 3,415,336 RESONATOR AND METHOD OF MAKING IT James C. Arthur and Raymond L. Placek, Columbus, Ind., assignors to Arvin Industries, Inc., Columbus, Ind., a corporation of Indiana Filed Nov. 14, 1966, Ser. No. 593,762 1 Claim. (Cl. 18148) ABSTRACT OF THE DISCLOSURE A sound attenuating resonator which is formed from an open-ended imperforate shell having a first pair of axially spaced reduced diameter shoulders and a second pair of axially spaced reduced diameter shoulders having a smaller diameter than the first pair of shoulders and disposed axially outwardly therefrom. A first perforated tube is carried within the shell and supported on its ends from a first pair of shoulders, and a second perforated tube is carried within the first tube with its ends supported on the second pair of shoulders.

This invention relates to a resonator for attenuating automotive exhaust noises and to a method of making it.

It is an object of the invention to provide a resonator which will have a plurality of sound attenuating chambers, which can be economically manufactured from metal-tubing, and which will prove sturdy and durable in use. It is a further object of the invention to provide a method of making a resonator having a plurality of coaxially aligned tubes which will retain said tubes in operative position in the resonator, and which can be carried out on a production line basis.

In accordance with one form of the invention, there is provided an elongated outer shell having a first pair of axially spaced, reduced diameter shoulders adjacent its ends. A first perforated tube is carried within the shell against said first pair of shoulders with one of its ends fixedly connected to one of said shoulders. The shell is provided with a second pair of axially spaced, reduced diameter shoulders disposed axially out-ward from said first pair of shoulders and having smaller diameters than said first pair of shoulders. And a second perforated tube is carried against said second pair of shoulders with one of its ends rigidly secured to one of said shoulders. In this manner, a first annular sound attenuating chamber is defined between said first perforated tube and the shell and a second annular sound attenuating chamber is defined between said first and second perforated tubes.

In forming such a resonator according to our invention, the shell has its diameter reduced at one of its ends to for-m a first shoulder, and the first perforated tube is inserted into said shell with one of its ends supported against said shoulder. The opposite end of the shell then has its diameter reduced to form a second shoulder disposed against the opposite end of said first tube. Said one end of the shell has its diameter further reduced to form a third shoulder axially outward from said first shoulder, and a second tube is inserted into said first tube with one of its ends supported against said third shoulder. Said opposite end of the shell then has its diameter further reduced to form a fourth shoulder axially outward from said second shoulder and disposed against said second tube. The first tube is rigidly connected to one of said first and second shoulders and said second tube is rigidly connected to one of said third and fourth shoulders so that said tubes are rigidly supported within the shell, but are free to expand and contract with changes in temperature of the resonator resulting from the exhaust gases moving therethrough.

Other objects and features of the invention will become apparent from the more detailed description which follows and from the accompanying drawings, in which:

FIG. 1 is a longitudinal section through a resonator embodying the invention;

FIG. 2 is an enlarged transverse section taken on the line 2-2 of FIG. 1; and

FIGS. 36 are longitudinal sections showing the successive deformations made in the resonator shell during the process of making the resonator shown in FIG. 1.

As shown in FIG. 1, our resonator is provided with an elongated, imperforate, open-ended shell 10. Adjacent its opposed ends, said shell is provided with a pair of reduced diameter annular shoulders 12 and 14. An elongated, open-ended, metal tube 16 provided with a plurality of louvered openings 17 is carried within the shell. The opposed ends of said tube are supported against the shoulders 12 and 14 with one of said ends being connected to the shoulder 14, as by spot welds 18, to rigidly secure it to the shell and the opposite tube end being free to slide along the shoulder 12 during expansion and contraction of the tube resulting from temperature changes imparted to the resonator by the exhaust gases moving therethrough. As shown, tube 16 is spaced from the shell 10 intermediate the shoulders 12 and 14 whereby said tube and shell define an elongated annular sound attenuating chamber 20.

A second pair of reduced diameter annular shoulders 24 and 26 are formed on shell 10 at its outer ends. As shown, shoulders 24 and 26 have smaller diameters than shoulders 12 and 14 and are disposed axially outwardly therefrom. A second elongated, open-ended metal tube 28 provided with louvered openings 29 is carried coaxially within tube 16. The tube 28 is larger than tube 16 and its outer ends project beyond the ends of tube 16 and are supported on shoulders 24 and 26. Tube 28 is rigidly connected to shoulder 26, as by spot welds 30, with its opposite end being free to slide along shoulder 24 to compensate for its expansion and contraction with changes in temperature. As shown, the tubes 16 and 28 define an elongated annular resonator chamber 32. The exhaust gases are free to flow into the chamber 32 through the louvered openings 29 in tube 28, and after entering chamber 32, are free to move into the chamber 20 through the louvered openings 17 in tube 16. If desired, one or both of the chambers 20 and 32 can be filled with a sound attenuating fibrous material. In the embodiment shown in FIG. 1, such a sound attenuating material 34 is carried in the chamber 20.

Tubes having louvered openings, such as 17 and 29, increase the difficulty of manufacture of a resonator. The louvers, by projecting outwardly from the tubes, prevent said tubes from being slid inwardly and outwardly in closely aligned tubes or apertured plates. Thus, it would be impossible to slide the tubes 28 through the reduced diameter shoulders 24 and 26 of shell 10 and still have said shell abut the tube around its circumference. Further, as shown in FIG. 2, tubes 16 and 28 are normally provided with lock seams 35 and 36, respectively. Such lock seams make deformation of the tubes 16 and 28 difficult and would thus make it extremely difiicult for said tubes to be bent into a connective relationship with an adjacent tube or shell. Therefore, in order to overcome these ditficulties and still provide the improved resonator structure shown in FIG. 1, we employ the method sequence illustrated in FIGS. 3-6.

As shown in FIGS. 3-6, in order to form the resonator shown in FIG. 1, shell 10 is placed in a draw die with one of its ends supported on a pilot 42. The opposite end of the shell is forced into the die 40 by a ram 43 to thus form the shell shoulder 14. After the shoulder 14 has been formed, tube 16 is inserted into the partially deformed shell with one of its ends being supported against the shoulder 14. As shown in FIG. 4, after the tube 16 has been inserted into the shell with one of its ends supported against shoulder 14, the shell and tube are placed in a draw die 44 with the lower ends of said shell and tube being supported by a pilot 46. Said shell and tube are forced into the die 44 by a ram 48 to thus form the shoulder 12 extending around the adjacent end of tube 16.

As shown in FIG. 5, after the shoulders 14 and 12 have been formed, the shell 10 with tube 16 supported within it is placed in a draw die 50 with the lower end of said shell being supported by a pilot 52. The shell and tube are forced into the die 50 by a ram 54 to form the shoulder 24. After shoulder 24 has been formed, tube 28 is inserted into the shell with its adjacent end being supported against said shoulder. As shown in FIG. 6, with tubes 28 and 16 in position in the shell 10, said shell is placed in a draw die 56 with one end of said shell and the tube 28 being supported by a pilot 58. The shell and tubes are then forced into die 56 by a ram 60 to form shoulder 26 against the adjacent end of tube 26.

When the shoulders 12 and 14 are formed, they abut the circumference of tube 16 at the adjacent ends thereof to support said tube within the shell. In a like manner, when the shoulders 24 and 26 are formed, they abut the circumference of tube 28 at its adjacent ends to hold it in position within the shell. After the two pairs of shoulders have been formed, tube 16 can be welded to shoulder 14 and tube 28 can be welded to shoulder 16 to thus rigidly connect each of said tubes to the shell at one of their ends. The opposite ends of said tubes are free to slide along shoulders 12 and 24 to compensate for expansion and contraction of the tubes.

When an acoustical material, such as the material 34 is employed, said material is disposed around tube 16 prior to its insertion Within the partially deformed shell 10. Similarly, if such an acoustical material is to be interposed between the tubes 28 and 16, said acoustical material is disposed around tube 28 prior to its insertion into the partially formed shell.

While we have described a resonator in which a pair of tubes are mounted to provide a pair of sound attenuating chambers, it is to be understood, of course, that 4 additional tubes may be employed to provide additional chambers. When such additional tubes are used, the shell will, of course, have to have additional pairs of tubesupporting shoulders formed at its ends, but such additional tubes can be inserted and the additional shoulders can be formed in the manner described herein.

We claim:

1.' A sound attenuating resonator, comprising an elongated open-ended imperforate shell, said shell having a first pair of axially spaced reduced diameter shoulders and a second pair of axially spaced reduced diameter shoulders having a smaller diameter than said first pair of shoulders and disposed axially outwardly therefrom, a first perforated tube carried within said shell and supported at its ends on said first pair of shoulders, and a second perforated tube carried within said first tube and projecting outwardly therefrom with its ends supported on said second pair of shoulders with said second pair of shoulders projecting beyond the ends of said second tube, said first tube being rigidly secured to one of the shoulders in the first pair and slidably supported in the other shoulder in said first pair, and said second tube being rigidly secured to one of the shoulders in said second pair and slidably supported on the other shoulder in said second pair.

References Cited UNITED STATES PATENTS 1,626,908 5/1927 Armstrong 181-49 1,709,426 4/1929 Beery 181-49 1,878,424 9/1932 Oldberg 181-42 XR 2,148,948 2/1939 Kingsley 181-55 2,251,369 8/1941 Moss 181-61 2,527,052 10/1950 Beck et al. 181-63 XR 3,175,640 3/1965 Matsui 181-48 XR 3,209,861 10/1965 Whitney 181-353 FOREIGN PATENTS 528,946 10/ 1958 Italy.

ROBERT S. WARD, JR., Primary Examiner.

US. Cl. X.R. 181-55, 61 

